Hello @Davood ,
This is an external query to discover DNS query types with SL characters, this may have sense to you depending on the hostnames, address in your company.
If not, this may be part of a range scan for vulnerabilities, so the best option will be to set firewall to block inbound requests of that type. You can easily set it up with Powershell, running the New-NetfirewallRule cmdlet. Here you have some examples:
Hope this helps in your case,
Best regards,